This, in turn, is accelerating the rate at which the forest is disappearing and turning into grassland.

Wide-scale burning by loggers and farmers has risen sharply over the past two decades, changing the region's cloud cover and reducing the amount of rain in some deforested areas that are turning into grassland or savanna.

"All the models indicate the same thing, 'savannisation'," Professor Pedro Leite Silva Dias of the University of São Paulo said at a conference on research on Amazon deforestation this week.

Silva Dias said the worst-case scenario for the Amazon is that at current burning and deforestation rates, 60% of the jungle will turn into savanna in the next 50 to 100 years. The most likely outlook is that 20% to 30% will turn into savanna, according to forecasting models.

Destruction of the Amazon, home to up to 30% of the globe's animal and plant species, reached its second-highest level last year.

An area of 5.9 million acres was destroyed as loggers and farmers hacked and burned the forest in 2003. About 85% of the Amazon is still standing.

Large-scale experiment

The Amazon scientists are presenting the latest findings of the Large Scale Biosphere-Atmosphere Experiment in Amazonia, the world's largest experiment on jungle deforestation.

The experiment, which includes U.S. space agency NASA, has found increasing evidence that the Amazon is slowly getting drier due to burning, with unpredictable consequences for its survival and weather patterns.

The experiment has monitored the Amazon since 1998, using research towers and a satellite imaging system.

As the climate becomes drier and reduces the colossal amount of water vapour over the Amazon, the effects will spread internationally, the experts said.

"Clouds over the Amazon are not in their normal state. The repercussions of this are going to be felt far away," said Professor Meinrat Andreae of Germany's Max Planck Institute for Chemistry. "This leads to significant changes of global [cloud] circulation."

Experts have found that burning of the Amazon, accounts for 75% of Brazil's greenhouse gas emissions, making Brazil one of the world's top 10 polluters.

The scientists said the Amazon's climate is already getting hotter due to global warming. Burning in the area itself is accelerating that process.